Rx7 cooling problems
 

I've purchased an Rx7 1992 model that had a total engine rebuilt 5 months ago from a reputable shop.

The following symtoms are evident:


After 1hr of driving, the temperature goes from middle to near red line!


When I try (from a cold start) and switch it to idling in garage only, after 10 mins (when the cooling fans turn on), coolant gushes out of the over flow tank.


I burp the system bu to no avail. I know that the previous owner installed an aluminum radiator after the rebuilding has been done.


What could be the problem?

Do you have an AST? where is the presure cap, AST or filler neck? If you don't have a AST do you have a presure cap on the filler neck?

[QUOTE=Rotary123;10706379After 1hr of driving, the temperature goes from middle to near red line!
[/QUOTE]


Stock temp gauge?

Yes stock temparature gauge. I also have a standard AST with the pressure cap on it.


I went to the mechanic today, we changed the radiator cap again with a different psi tollerance. I took it for a spin (30mins) after it was around 10mins idling.

I parked it in the garage (still idling), not one single drop from the overflow tank. When I switched the rx7 off, I heared boiling/churning sounds, and quarter of the coolant gushed out from the oferflow.

Are the water seals the main culprit?

If you've seen the stock gauge get to near "red-line" then you've seriously overheated the engine and likely damaged a coolant seal. A failed/damaged coolant seal would then explain the pressurized and overflowing over-flow tank.
The high-pressure cap that was installed at the garage isn't going to help and the boiling sounds you hear at shut down is a result of heat-soak and air in the system. This in-turn will cause more temp spiking. From here it's probably going to be a continued cycle of overheating until a rebuild for the coolant seals.

The stock gauge is not linear and once it moves from just under the half-way mark it's almost too late. Get an aftermarket gauge. And stop if it ever get's past about 110 C.

Coolant seals. Rebuild time.

-Geoff